The solar system's farthest known planetary outpost is closer to getting its first visitor. Recently, NASA gave Johns Hopkins' Applied Physics Laboratory, Southwest Research Institute and their partners the go-ahead to start full development of the first mission to Pluto and the Kuiper Belt.

The New Horizons spacecraft is scheduled to launch in January 2006, swing past Jupiter for a gravity boost and scientific studies in 2007 and reach Pluto and its moon, Charon, as early as summer 2015. The arrival date depends on the launch vehicle NASA selects this summer for the mission--either a Boeing Delta 4 or Lockheed Martin Atlas 5.

After a six-month encounter with Pluto-Charon--during which New Horizons will characterize Pluto's and Charon's global geology and geomorphology, map their surface compositions and temperatures, and examine Pluto's complex atmosphere--the spacecraft will head deeper into the Kuiper Belt to study one or more of the icy miniworlds in that vast region, at least a billion miles beyond Neptune's orbit.

"We've designed the mission, the spacecraft and the instruments, and we're ready to start cutting metal," said APL's Thomas Coughlin, New Horizons project manager. "This is the time in a mission when things really start rolling toward launch. We have less than three years to go, and there is a lot to do between now and then--and we're excited to get moving on it."

APL manages the mission for NASA and will design, build and operate the New Horizons spacecraft. Alan Stern, director of the Southwest Research Institute's Department of Space Studies in Boulder, Colo., is the mission's principal investigator and leads an unprecedented science effort. "This is exploration at its greatest, as only the U.S. space program can do," Stern said. "New Horizons will reconnoiter the great, unexplored 'third zone' of our solar system and make a historic flyby of the outermost known planet."

NASA tapped the APL-SwRI team to conduct its Pluto-Kuiper Belt mission in November 2001, and preliminary design work began in January 2002.

David Kusnierkiewicz, New Horizons mission systems engineer at APL, said, "The systems and instruments have all been on the drawing board, and we've gone over many details. Now we've honed in on specific designs, and we're ready to start putting systems and instruments together."

Assembly has already started on New Horizons' scientific instruments, and the team will begin fabricating parts of the spacecraft's structure next month. Baseline plans for the mission include use of a radioisotope thermoelectric generator, which could supply more than 200 watts of electrical power for the spacecraft. The mission's next major milestone is a critical design review in early August; if that goes as expected, spacecraft integration and testing would begin in May 2004.

That date will come two months after the scheduled launch of another APL spacecraft--the MErcury Surface, Space ENvironment, GEochemistry and Ranging satellite, known as MESSENGER--which is set to become the first spacecraft to orbit Mercury. Now under construction at APL, MESSENGER will launch aboard a Delta 2 rocket from Cape Canaveral Air Force Station, Fla., in March 2004 and begin a yearlong orbit study of Mercury in April 2009.

"We have the unique opportunity to complete the exploration of the planets, while traveling to the solar system's extremes," said Stamatios Krimigis, head of the APL Space Department. "Before the end of the decade we are going to visit the largely unexplored innermost planet, where surface temperatures are near 845 degrees Fahrenheit and the thermal environment for our spacecraft will be rather demanding. And we're leading a mission to the outermost planet, where estimated temperatures are minus 390 degrees Fahrenheit. It's an incredible challenge and a chance to make history."

The New Horizons mission team also includes major partners Stanford University, Ball Aerospace, NASA Goddard Space Flight Center and the Jet Propulsion Laboratory. SwRI, headquartered in San Antonio, is responsible for scientific instrument development, science team management and the mission's scientific investigations.

For more on the New Horizons mission, go to http://pluto.jhuapl.edu. For a look at the MESSENGER mission, including live Webcam images of the spacecraft's construction, go http://messenger.jhuapl.edu.